Personally, I think that extra piece on the grip is a Pachmayr one from when they made things in CA. My dad's Colt snub has the same item on it.
As to 38Spl. ammo; any of the ammo marked on the box as "38 Special", or "38 Smith & Wesson Special" or "38 S&W Special" will all be the same. Typical load was a 158 grain bullet. More modern loading seem to favor a lighter 125 grain bullet. I know all of my 38 and 357s prefer the 158 gr LSWC (Lead Semi Wadcutter) design for accuracy.
You have a great revolver and an excellent choice for concealed carry